1. Field of the Invention
The present invention relates to an air separator system for de-aerating fluid, and in particular, a system for use in conjunction with a fuel dispenser for de-aerating liquid fuel.
2. Description of the Related Art
Fuel dispensers contain a fuel storage tank, a fuel pump, and a fuel meter. The fuel pump, conducts fuel from the fuel storage tank and the meter measures the volume of fuel to be dispensed. Liquid fuel may contain dissolved gasses, for example, components of ambient air such as oxygen, nitrogen, etc., as well as hydrocarbons. These dissolved gasses contribute to the volume of fuel pumped from the fuel storage tank. In order to get an accurate measurement of the volume of liquid fuel to be dispensed, dissolved gasses must be removed from the fuel before metering. In addition, many fuel dispensers manufactured today contain a vapor recovery system. The vapor recovery system includes a vapor recovery pump for evacuating fuel vapors from the fuel tank of a vehicle being refueled.
Traditionally, fuel dispensers contain a gas or an air separator disposed downstream from the fuel pump. The fluid on the inlet side of the pump is in a vacuum and, consequently, the pressure is less than atmospheric air. The low pressure hampers effective air separation and removal. Conversely, the pressure on the downstream or outlet side of a fuel pump is greater than atmospheric air. Therefore, traditional fuel dispensers locate the air separator on the outlet side of a pump where the pressure is higher.
One problem with traditional fuel dispenser air separation systems is that the air separation system is located on the outlet side of a fuel pump. The pressure on the downstream or outlet side of a fuel pump is greater than atmospheric air. Pressure higher than atmospheric air assists in the removal of gasses liberated from liquid fuel. However, a less than atmospheric pressure on the inlet side of a pump hampers removal of liberated gasses in an air separator system. Consequently, many current air separation systems will not operate if located on the inlet side of a pump. Therefore, traditional fuel dispensers locate an air separation system on the outlet side of a fuel pump where the pressure is greater than atmospheric air.
A second disadvantage of current fuel dispensers air separator systems are that they do not contain a unified pump/meter unit. A unified pump/meter unit volumetrically measures the volume of fuel pumped for accurate measurement of the volume of fuel dispensed from a fuel dispenser. To accurately measure the volume of fuel to be dispensed, air and other dissolved gasses must first be removed from the liquid fuel before measuring the fuel volume. Since traditional fuel dispensers remove air and gasses on the outlet side of a pump, the meter must be located on the outlet side of a air separation system in order to get more accurate measurement. Consequently, traditional fuel dispensers do not contain a unified pump/meter to both pump fuel and provide an accurate measurement of fuel dispensers.